1. Field of Art
The present invention relates to a magnetic recording member and the process for manufacturing the same, wherein a lubricant layer laid on the top face of the magnetic recording member is chemically coupled through an intermediate layer of aminosilane or epoxysilane compound with the magnetic storage layer to form a permanent overlaying layer, and wherein the lubricant layer is uniformalized and improved in durability by setting or solidification.
2. Prior Art
A so-called contact start stop system (CSS system) is adopted generally as the magnetic disc drive system. In the CSS system, a recording-reproducing head slider contacts with the surface of a magnetic storage disc in the stand-by condition where the disc is stopped, and an air gap is formed between the head slider and the surface of the disc, upon rotation of the disc at a present speed, to disengage the head slider from the disc during the recording or reproducing operation. However, the disc and the head slider are apt to be abraded or weared at the time when the head slider takes off the surface of the disc, or the head slider contacts accidentally with the surface of the rotating disc during the recording or reproducing operation when it must be floated above the surface of the disc, whereby the surface of the head slider or the disc could be scratched or otherwise damaged. In order to protect the head slider and the disc from such abrasion-wear or scratch, particularly for the protection of storage medium on the magnetic recording disc, it has been proposed to cover the magnetic layer by a lubricant layer. However, if an excessively large amount of a liquid lubricant is applied on the top of the magnetic disc, stickness between the head slider and the surface of the disc becomes too high to cause a so-called head slider crash at the time of initiation of disc drive, leading to breakdown of the head slider or damage of the disc.
With the aim of overcoming the aforementioned problems, provisions were made to form the following lubricant layers on the magnetic discs. For instance, U.S. Pat. No. 4,069,360 discloses a magnetic record member protected by a combination of an amorphous inorganic oxide layer formed on the thin film of a magnetic metal medium and a silicon-containing lubricant layer coated over the amorphous inorganic oxide layer so that the lubricant adheres to the inorganic oxide layer, the lubricant layer containing a silicon base oil or silicon type surface coupling agent. U.S. Pat. No. 4,152,487 discloses a magnetic record member comprising a non-magnetic alloy disc substrate, a thin film of a magnetic metal medium applied on the substrate, and a protection polysilicate layer covering the magnetic metal medium. The protection polysilicate layer is made of a dehydration condensation polymerization product of tetraalkoxysilane or tetrahydroxysilane added with a stress relaxation agent. The stress relaxation agent is a silane coupling agent or a surface coupling agent having a functional groups selected from --COOH, --NH.sub.2, --SH, --COOR, --NHR, .dbd.NH, --CHO, --NCO, --SiOH, Si--OR, Si--X, ##STR1## --CH.sub.2 OH, ##STR2## --O--CO--R and --OH, wherein R is an alkyl and X is a halogen.
It is known to use, as a lubricant for magnetic recording disc, fluorinated polyethers having high fluorine content and represented by the following general formula of: ##STR3## wherein n is an integer. Polymers of this type are commercially available from E. I. du Pont de Memours under the Trade Name "Krytox 143 Fluorinated Oils". Further, U.S. Pat. No. 4,268,556 discloses the use of a fluorinated polymer having alow molecular weight and containing known functional groups at the terminal ends thereof, as the lubricant for magnetic recording disc. The polymer is a polyether having a skeletal chain unit selected from --CF.sub.2 --O-- or --CF.sub.2 --CF.sub.2 --O-- and having a polar terminal group selected from --COOR, CONRR', --CH.sub.2 OH, --C.sub.6 H.sub.12 NRR', --COC.sub.n F.sub.2n+1, C(OH).sub.2 C.sub.n H.sub.2n+1.
However, silicon oil base or other certain type lubricants tend to migrate from the center portion to the marginal portion of the magnetic disc during the operation when the disc is driven to rotate at high speed, resulting in uneven thickness of the lubricant layer. With such a lubricant layer having uneven thickness distribution, prevention of abrasion, head slider crash, or collision between the head slider and the magnetic recording medium of the disc cannot be effectively realized.